SDS100/SDS200: SDS200 went silent

[W5KYP]

The SDS200 has a choke on the PS cable, this will eliminate any RFI from the SDS200 wall-wart however, the Dell G2724D monitors have built-in power supply, no wall-wart. I turned off the monitors with the power button and the RFI was still present. It wasn't until i physically unplugged each monitor that the RFI disappeared.

Will be adding ferrite cores to the power cable of the monitors to try and eliminate the RFI.

 

[Ubbe]

It wasn't until i physically unplugged each monitor that the RFI disappeared.

Try to instead unplug their HDMI cable from the monitors and see if that helps. Logically it should be that cable that needs to have extra ferrites on them, or a higher quality cable that are better shielded.

/Ubbe

 

[W5KYP]

@Ubbe

I did not think of the video cables. In my case, I purchased high quality Displayport cables.
Nevertheless, I will try removing the cables and see what happens.

Appreciate the tip!

 

[cavmedic]

Don't just order generic ferrites, order the correct mix for the frequencies you need to attenuate. You might have to mix the mix to cover the broad range of frequencies.


MIX CHART

 

[gary123]

The Rf may be radiating directly from the boards in the monitors. You may have to get creative to shield them from radiating the signal. Keep us in the loop.

It is sad to say but RFI is becoming a real issue all over the place. Many manufacturers do not shield or add filtering in order to keep the costs down. Saving that.01 cent on each unit is more important that having a clean product.

 

[Ubbe]

Don't just order generic ferrites, order the correct mix for the frequencies you need to attenuate. You might have to mix the mix to cover the broad range of frequencies.


MIX CHART

And also radio frequencies are a wave with a peak at each 1/2 wavelength and it's there that a suppressor like a ferrite works best. As you do not know where that peak is you will have to cover the whole 1/2 wavelength. With a more thinner and flexible cable you make the cable go several turns thru the ferrite to get a bigger chance of hitting that peak.

At 800MHz it's something like a 7 inch length and at 400MHz it's double that and at 150MHz it's a 6 times longer 1/2 wave.

/Ubbe

 

[W5KYP]

I will be using a spectrum analyzer to determine pinpoint the RFI and address accordingly.

 

[gary123]

When you find it post. Some of us may be able to make suggestions on solutions we have used in the past. This may save you time R&Ding a solution or going down a blind alley.